When a data packet sent to a user is routed, according to the Internet Protocol (IP), to a packet data network gateway (PGW) to enter an operator network, a transmission process using the PGW as an example is as follows:
In a data transmission process, decapsulation is performed from a lower layer to an upper layer and encapsulation is performed from the upper layer to the lower layer. Therefore, when data is routed according to the IP to enter the PGW, decapsulation is started from the lower layer, that is, decapsulation is performed layer by layer from a link layer, a network layer, a transport layer and an application layer. After decapsulation is performed at an IP layer, destination address information is determined according to header information of a data packet, and then the data is transmitted to the transport layer. After decapsulation is performed at the transport layer, source port information and destination port information are determined, and then the data is sent to the application layer. Information about a bearer required for sending the data is determined at the application layer.
The PGW determines, in a data decapsulation process, information about a next hop to which the data is transmitted and logical channel information required for transmitting the data packet to the next hop. In this case, the PGW encapsulates the decapsulated data and then sends the encapsulated data to the next hop by using the bearer. A specific encapsulation process is as follows: GPRS Tunneling Protocol-User Plane (GTP-U) encapsulation is performed at the application layer; the data is sent to the transport layer for User Datagram Protocol (UDP) encapsulation, and then enters the network layer for IP encapsulation; then encapsulation at the link layer is performed; and finally, the data is transformed into an electrical signal and the electrical signal is transmitted at a physical layer.
However, this transmission manner results in a great waste of resources. In one aspect, a process in which the PGW or another network element in the network continuously performs encapsulation and decapsulation in the data transmission process results in huge processing overheads; in another aspect, addition of UDP/GTP-U encapsulation at an outer layer of the data packet increases at least 40 bytes of overheads, and for increasing small packet services in the future, such huge overheads may exceed a length of valid information, thereby resulting in huge transmission overheads.